Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> Yes, 64 looked like the appropriate value too. Actually, I was
> surprised to see as much of a slowdown as we did.
I was too. pgbench runs the same backend(s) throughout the test,
so it shouldn't be paying anything meaningful in disk I/O for the
larger catalog size. After the first set of queries all the relevant
catalog rows will be cached in syscache. So where's the performance
hit coming from?
It'd be interesting to redo these runs with profiling turned on
and compare the profiles at, say, 32 and 512 to see where the time
is going for larger NAMEDATALEN. Might be something that's easy
to fix once we identify it.
regards, tom lane